Combined tanning and dyeing process.



FRANZ WAL'IHER WAR'IENBERGER, or ALTONA, GERMANY.

. COMBINED TANNING AND DYEING PROCESS.

SPECIFICATION forming part of Letters Patent N 0. 658,032, dated September 18, 1900.

Application filed September 80,1899. Serial No. 732,233. on specimens.

To all whom it may concern.-

Be it known that 1, FRANZ WALTHER WAR TENBERGER, a subject of the King of Prussia, German Emperor, residing at No. 11 bei der Johanniskirche, Altona, in the Province of Schleswig-Holstein and German Empire,have invented a certain'new and useful Combined Tanning and Dyeing Process, of which the following is a specification.

The present invention relates to the art of tanning and dyeing skins; and it has for its object a process whereby the tanning and dyeing of skins may be combined and efiected simultaneously in a most expeditious and-yet thorough manner.

With this end in view my improved process consists, first, in subjecting the skins or hides which have been prepared for tanning by the usual liming and hating processes to the action of a weak aqueous .solution of picric acid, to which the dyestuffs, such as anilin colors, have been added, so that the picric acid,as well as the dyestuff, may act simultaneously upon the skins; and, second, in subjecting the thus simultaneously tanned and dyed hides or skins to the action of a solution of hyposulfite of soda (N21 S O +5H O) or other reagent in order to fix not only the picric acid, but also the dye. The skins tanned and dyed are then finished for market by beating, rubbing, scraping, &c.', in the usual manner. The essential feature of this invention lies, therefore, in the use of a highly-diluted solution of picric acid, into which is incorporated the dyestufi-that is to say, in the simultaneous application of picric acid and dyestuff and in the subsequent treatment with a suitable reagent for fixing both the picric acid and the dye in the simultaneously tanned and dyed hides;

The carrying into practice of my improved combined tanning and dyeing process is very simple, and the steps necessary to make a marketable leather are as follows: The hides or skins previously prepared by the usual liming and bating processes are steeped in a combined tanning and dyeing solution, which may be obtained by mixing about seven hundred parts, by weight, of water, ten parts, by weight, of picric acid, and one part, by weight, of thedesired anilin dye or color at ordinary temperature, which in some cases may be raised to about 30 centigrade and maintained at this temperature during the tanning and dyeing process. The duration of the latter depends upon the nature and weight of the hides and varies, accordingly, from about two to four hours. Practical experiments have shown that by this operation not only an elfectual tanning but also a most excellent coloring of the hides is obtained,

picric-acid solution acts at, the same time as a carrier for the dye, and thereby enables the latter to better and more uniformly permeate the pores of the grain of the skins than would be the case if the latter were dyed after having been tanned. When the hides are thoroughly tanned and Well dyed, they are removed from the combined tanning and dyeing liquor and subjected to a subsequent treatment, which consists in rinsing the leather in'a solution of about twenty parts of water, about four parts of hyposulfite of soda, (Na S O -l-5H O,) and about one to three parts of hydrochloric acid. The hyposulfite solution or other equivalent agent has the effect of fixing the picric acid, of depriving the latter of its discoloring and poisonous properties, and of fixing the color or dye. After this treatment the leather is washed and then curried in the usual manner.

Having thus described my invention, what I claim as new therein, and desire to secure by Letters Patent, is

1. The process of simultaneously dyeing and tanning hides and skins, previously prepared for tanning in the usual manner, which consists in subjecting the same to the action of a solution of a dyestuif and of an acid tanning agent incapable of fixing the dyestufi, and subjecting the dyed and tanned hides or skins to the action of a solution of a reagent capable of fixing both dyestuff and acid tanning agent.

2. The process of simultaneously dyeing and tanning hides and skins, previously prepared for tanning in the usual manner, which consists in subjecting them to the act-ion of a dyestuff and picric acid'and subjecting the dyed and tanned hides or skins to the action of a solution of a suitable hyposnlfite and hydrochloric acid.

3. The process, which consists in subjectwhich is accounted for by the fact that the i ICO ing hides or skins, previously prepared for of a weak solution of picric acid containing" :6 tanning by the usual processes, to the action a suitable dyestuif, and then to the action of of asolution of about ten parts of picric acid, a solution of a hyposulfite and hydrochloric of about seven hundred parts of water, and acid, substantially as and for the purpose 5 of about one part of anilin dye or color, subset forth.

stantially asand for the purpose set forth. FRANZ WALTHER WARTENBERGER:

4. The process, which consists in subject- \Vitnesses:

ing hides or skins, previously prepared for ALEXANDER SP'ECHS,

tanning by the usual processes, to the action a: E. H. L. MUMMENHOFF; 

